From Bill Chamlee at the Cleveland VA:
I stumbled onto your site while researching the new lower potency heparin/therapeutic range issue. I was interested in your quick question about checking for clots. I don’t do any of the four choices you list. I use two applicator sticks to check for clots after centrifuging and running first. The sticks can act as an activator and my experience is that the PTT is usually shorter after rimming for clots, more noticeably of course in abnormal and therapeutic specimens. And I still don’t understand how you can identify a clotted specimen by looking at the test results. Sure, sometimes the low PTT is a dead giveaway. But not always–the normal looking PTT could really be high. And what if it’s only a PT–INR? I know CAP lists that as an acceptable choice, but I don’t know why. With my method, I have seen plenty of clotted specimens with perfectly “plausible” results. But are they accurate results? I reject them. So does CAP imply clotted specimens are OK if they give plausible results?
And as for visually looking for clots, well between the numerous labels covering our tubes and my old eyes, I am not sure I would see big clots, much less small ones. Yes, it is riskier to uncap each specimen and rim, especially since we have a cap piercer and wouldn’t otherwise have to uncap. And it is also more time consuming and costly. But I am convinced it is the best way to identify clotted specimens for coag testing. I also take a good look at each specimen for total volume and liquid volume (HCT) which could disqualify it and hemolysis in which case we comment. I would be very interested in your feedback on all these issues. Has my OCD gotten the best of me?
Thanks-Bill Chamlee-Cleveland VA
Thanks for your comments, Bill, and welcome to Fritsma Factor. The idea of “visual inspection” has always bugged me, even before our tubes became completely wrapped with labels, who could see a clot well in whole blood? I like your approach, and invite others to chime in with their approach.
I was talking just this morning with frequent contributor Dave McGlasson about applicator sticks and activation. He, like you, is convinced the sticks activate platelets and together we’ve been trying to develop a research plan assessing platelet activation in association with sticks. We’d also like to learn how much platelets become activated by centrifugation, particularly as it relates to preparing specimens for light transmittance aggregometry. Your comment helps confirm our ideas. Geo.